It has long been the practice in gas-fired heating appliances having a pilot light, such as water heaters, furnaces and clothes driers, (hereinafter collectively referenced as, gas appliances) to utilize a gas control valve that includes a magnetically operated safety valve for shutting off the flow of gas if the pilot light should be extinguished. Such magnetically operated safety valves typically include a device known in the industry as an automatic pilot valve magnet that is connected to a thermocouple exposed to the pilot light flame.
The pilot valve magnet is an electrically operated solenoid valve, having a valve poppet mounted on a movable armature, and an electrical coil that generates a magnetic flux for moving the armature when an electrical current is applied to the electrical coil. The electrical coil is connected to the thermocouple in such a manner that, when the pilot light is heating the thermocouple, and causing it to produce a flow of current through the electrical coil, the valve poppet is held in an open position allowing a flow of gas through the control valve. The pilot valve magnet also includes a spring for biasing the armature and poppet toward a closed position of the valve, so that if the pilot light is extinguished, thereby causing the thermocouple to stop providing and electrical current to the electrical coil of the pilot valve magnet, the spring will move the armature and poppet to the closed position of the valve, to thereby cut off the flow of gas through the gas control valve. A mechanism is also typically provided in the gas valve for mechanically opening and holding the poppet in an open position while the pilot light is being lit, and for a minute or so after lighting, while the pilot light flame is heating the thermocouple to a high enough temperature that the current it is producing will hold the valve poppet open.
It has also been the practice in some gas appliances to provide an electrical cut-off (ECO) switch, connected in a series electrical circuit relationship between the thermocouple and the automatic pilot valve magnet, for interrupting the flow of current from the thermocouple to the pilot valve magnet when the ECO switch is open, regardless of whether the pilot valve is burning or not. Such ECO switches are often actuated by bi-metallic elements that open the ECO switch in the event that an over-temperature condition occurs in the gas appliance. In a water heater, for example an ECO switch is often used for cutting off flow of gas through the gas control valve, if the temperature of water in the water heater rises above a predetermined maximum temperature.
FIGS. 1 and 2 illustrate the manner in which the series electrical connection of the ECO switch between the thermocouple and pilot valve magnet has typically been accomplished in the past, in a manner that is also generally described in U.S. Pat. Nos. 3,286,216 and 3,286,923, to Jackson, et al.
FIG. 1 shows a prior control apparatus 110, configured for installation into a bore 112 of a valve housing 114 of a gas control valve 100 for a gas appliance (not shown) having an electrical cut-off (ECO) switch (not shown). The prior control apparatus 110 includes an automatic pilot valve magnet 116, an ECO connector 118, and a crimp-on retainer 120.
The pilot valve magnet 116 includes an externally threaded portion 122 thereof for engaging mating threads 124 in the bore 112 of the valve housing 114. The interior end (not shown) of the bore 112 includes a valve seat (not shown) that is closed when a poppet 126 attached to the armature 128 of the pilot valve magnet 116 is moved to an extended position by a biasing spring 130 of the pilot valve magnet 116.
An exposed end 131 of the pilot valve magnet 116 extends outward from the valve housing 114, when the control apparatus 110 is installed in the bore 112, and includes a threaded central bore 132 for receiving a threaded coupling 134 of a thermocouple 136. A transversely extending slot 138, opening axially outward from the exposed end 131 of the pilot valve magnet 116, extends diametrically across the exposed end 131 end of the pilot valve magnet 116, for receipt therein of the ECO connector 118. The ECO connector is installed into the transversely extending slot 138 prior to installation of the control apparatus 110 into the bore 112, and is clamped in place by the crimp-on retainer 120, which has a lip 140 that is crimped into an annular groove 142 in the exposed end 131 of the pilot valve magnet 116, as shown in FIG. 2.
As shown in FIG. 1, the ECO connector 118 includes a central, cylindrical shaped, annular section 144, having an outer periphery configured to slide into the threaded central bore 132 in the exposed end 131 of the pilot valve magnet 116. The inner periphery of the annular section 144 of the ECO connector 118 defines a blind hole 146 for receiving an electrical terminal 148 of the thermocouple 136.
As shown in FIG. 2, the ECO connector 118 includes a first and a second ECO switch contact 150, 152, electrically isolated form one another by a layer of insulation 151. The layer of insulation 151 may either be part of a housing of the ECO connector, or a separate piece of insulation. The second ECO switch contact 152 mates with the electrical terminal 148 of the thermocouple 136. The first ECO switch contact 150 mates with an electrical terminal 154 of the pilot valve magnet 116 that is located at the bottom of the slot 138 in the exposed end 131 of the pilot valve magnet 116.
Although the control apparatus 110 described above has been used with great success for many years, there are some areas in which improvement is desirable.
For example, having the pilot valve magnet 116 configured to include such features as the externally threaded portion 122, for retaining the control apparatus 110 in the bore 112 of the valve 114, the threaded central bore 132, for receiving the thermocouple 136, the extending slot 138, for receiving the ECO connector 118, and the annular groove 142, for receiving the crimped edge 140 of the crimp-on retainer 120, add considerable complexity and cost to the pilot valve magnet 116. The pilot valve magnet 116 configuration is also typically unique to a particular gas valve 114, thereby precluding the use of a standardized pilot valve magnet that could be used in several gas control valves of differing configuration, to thereby reduce cost by increasing production volumes and reducing inventory.
Having the ECO connector 118 mounted in the slot 138 of the exposed end 131 of the pilot valve magnet 116 also undesirably increases the distance that the exposed end 131 extends from the valve 114. An additional problem is also created by this arrangement, with regard to installation of the pilot valve magnet 116 and routing of wires 156, 158 extending from the first and second ECO switch contacts 150, 152, because, as the pilot valve magnet 116 is threaded into the bore 112 of the control valve 114, the wires 156, 158 rotate with the pilot valve magnet 116, and may not be oriented in an optimal direction for connection to the ECO switch when the pilot valve magnet is tightened to its final position.
What is needed is an improved control apparatus for a gas control valve that solves one or more of the problems described above.